O&O DiskImage 8
Data comparison with checksums

Unchanged data resulting from incremental images is saved using checksums by default. Such a file will be slightly larger. That's why it's enough, when creating the next incremental image, to use an existing incremental image (with checksums) as the base image. This function is activated by default. If you save all images in a single folder, you can deactivate this function. Your images will then take up less space on disk.

Please make sure that the function Use checksums to administer unchanged data under Drive imaging/Imaging options/Advanced is enabled.